A need exists for additional methods to prepare 2-substituted-5-oxo-3-pyrazolidinecarboxylates. Such compounds include useful intermediates for the preparation of crop protection agents, pharmaceuticals, photographic developers and other fine chemicals. U.S. Pat. No. 3,153,654 and PCT Publication WO 03/015519 describe the preparation of 2-substituted-5-oxo-3-pyrazolidinecarboxylates by condensation of maleate or fumarate esters with substituted hydrazines in the presence of a base. However, alternative methods providing potentially greater yields are still needed.